Hydrogen peroxide has an oxidizing power such that it exhibits strong bleaching and germicidal actions. Therefore, hydrogen peroxide is utilized as a bleaching agent for, for example, paper, pulp, and fibers, or as a germicide. Further, hydrogen peroxide is an important industrial product widely used in oxidation reactions including epoxidation and hydroxylation.
Further, hydrogen peroxide is used in the semiconductor industry, specifically used in, for example, cleaning of the surfaces of semiconductor substrates and the like, chemical polishing of the surfaces of copper, tin, and other copper alloys, and etching for electronic circuit. Hydrogen peroxide produces only water and oxygen as decomposition products, and hence is considered important from the viewpoint of green chemistry, and has attracted attention as a substitute material for a chlorine bleaching agent.
Although hydrogen peroxide is currently synthesized industrially by an anthraquinone process, since this process consumes a large amount of energy, there is a need to develop a new synthesis method.
As one alternative method, there has been considerable activity in the development of a method for synthesizing hydrogen peroxide directly from hydrogen and oxygen. Non-homogeneous solid catalysts have typically been developed for use as catalysts of this direct synthesis method, and various non-homogeneous solid catalysts have been reported. For example, Patent Document 1 and Non-Patent Document 1 disclose that hydrogen peroxide is synthesized directly from hydrogen and oxygen using an alloy solid catalyst such as platinum-palladium.
In addition, organometallic complexes, in which various ligands are used for the metal elements such as members of the platinum group or iron group, have also been proposed for use as catalysts for direct synthesis of hydrogen peroxide (Patent Documents 2 and 3).